Adjustable scaffold



Se t. 2, 1969 F. a. WHiSLER ADJUSTABLE SGAFFOLD Filed March 29, 1968 2 Sheets-Sheet 1 INVENTOR. Forrest B. Wh/s/er ATTORNEYS p 2, 1969 F. B. WHISLER 3,464,519

ADJUSTABLE S CAFFOLD Filed March 29, 1968 2 sheets-sheet 2 FIG/l INVENTOR.

F arms? 8. Whisler 4/ BY 34 345 MB 35 A T TORNE Y8 United States Patent US. Cl. 182-441 6 Claims ABSTRACT OF THE DISCLOSURE A mobile, adjustable scaffold which carries upon a wheel-mounted base a lazy-tong elevator supporting a scaffold deck. The elevator is operated by an actuator mounted in the base. To complete the organization, a ladder is secured to the deck to provide easy access thereto and stabilizing struts are provided at each side of the deck to extend downwardly therefrom to connect with the base and to rest upon the ground surface. The stabilizing struts, incorporated in the organization to eliminate vertical movement and lateral instability of the elevator, are formed as telescopic members which are adapted to be extended as the elevator raises the deck and which include directional locking means adapted to permit the struts to be extended as the deck is raised, but to prevent retraction of the struts thereafter.

This invention relates to scaffolds, and more particularly to portable, adjustable scaffolds. A primary object of the invention is to provide a novel and improved adjustable scaffold which may be quickly and easily moved to a given location and thereafter, extended upwardly to any selected height.

Another object of the invention is to provide a novel and improved adjustable scaffold which advantageously and easily set, extended for use and thereafter retracted, and which, when extended, reaches to a substantial height, but when retracted, is a small, compact, lightweight unit capable of being easily transported in a pickup truck or the like and of being stored in a small space as within an ordinary room.

Another object of the invention is to provide a novel and improved adjustable scaffold which advantageously uses a lazy-tong elevator for supporting and for raising and lowering the scaffold deck.

Another object of the invention is to provide, in an adjustable scaffold which uses a lazy-tong mechanism to support, raise and lower the scaffold deck, a novel and improved arrangement of stabilizers associated with the lazy-tong elevator to obviate and eliminate the characteristic lateral instability of a lazy-tong type mechanism.

Another object of the invention is to provide a novel and improved extendable stabilizer for a lazy-tong elevator which permits the elevator to be used as a scaffold or the like and which may operate in unison with the lazy-tong elevator to stabilize the same at any selected extension of the structure.

Other objects of the invention are to provide a novel and improved adjustable scaffold, using a lazy-tong elevator and a stabilizer associated therewith, which is a simple, versatile, rugged, neat appearing, low cost structure.

With the foregoing and other objects in view, my present invention comprises certain constructions, combinations and arrangements of parts and elements as hereinafter described, defined in the appended claims, and illustrated in preferred embodiment by the accompanying drawings in which:

FIGURE 1 is a side elevational view of a preferred embodiment of the improved scaffold extended to substan tially its full height.

FIGURE 2 is a front elevational view of the extended scaffold shown at FIG. 1, but with a portion broken away to show parts otherwise hidden from view.

FIGURE 3 is a side elevational view of the unit shown at FIG. 1, but with the scaffold being retracted and with the ladder and other portions of the components being disconnected or removed.

FIGURE 4 is a transverse sectional view of one side of the apparatus and an edge view of a stabilizer leg, as taken from the indicated line 44 at FIG. 3, but on an enlarged scale.

FIGURE 5 is a side view of a portion of the retracted stabilizer leg, as taken from the indicated arrow 5 at FIG. 4, but on a further enlarged scale.

FIGURE 6 is a fragmentary view of a portion of the stabilizer leg from the indicated line 6-6 at FIG. 1, but on an enlarged scale.

FIGURE 7 is a fragmentary, edge view supplementing the portion shown at FIG. 6, as taken from the indicated arrow 7 at FIG. 1, but on an enlarged scale.

FIGURE 8 is a sectional plan view as taken from the indicated line 8-8 at FIG. 1, but on an enlarged scale.

FIGURE 9 is a fragmentary sectional detail as taken from the indicated line 99 at FIG. 8, but on an enlarged scale.

FIGURE 10 is a fragmentary sectional detail as taken from the indicated line 10-10 at FIG. 8, but on an enlarged scale.

FIGURE 11 is a fragmentary side view of a stabilizing leg supplementing the showing at FIG. 10, as taken from the indicated arrow 11 at FIG. 8, but on an enlarged scale.

Scaffolds of various types are necessarily used extensively in the construction and maintenance of buildings and in a number of related activities where a workman must be above the ground level. To meet the need for various scaffolds, there has been developed an industry of providing scaffolds of the general type which are formed as tubular sections adapted to be secured together as a frame work. Planks are then set within and upon this framework to provide platforms or decking. This arrangement has three disadvantages. In the first place, the scaffolds require substantial time to prepare and are semipermanent structures to be set up and used for a substantial time period. Secondly, they are arranged in modulator sections of selected height and are limited in their versatility. Also, planks on this type of scaffold are usually loose creating a well known hazard. Thus, there is a real and definite need for a more flexible scaffold structure especially for jobs of short duration. On such jobs, it is necessary to quickly install the scaffold, adjust it to a selected height and then, after the job is completed, move it to the next location.

The present invention was conceived and developed to meet this need and comprises, in essence, a wheelmounted base carrying a lazy-tong elevator, which, in turn, supports a deck. The lazy-tong elevator is raised and lowered by either a manual or motorized drive as desired.

A lazy-tong mechanism per se, is well known. However, such has not been used as an elevator to support scaffold deck, for it has been found that the lazy-tong mechanisms, as such, cannot be formed with sufficient side stability to serve such a purpose. It was found that, regardless of how tight the connections were made between the cross links of a lazy-tong elevator, and regardless of how firm it was secured to base, sidewise instability of the elevator could not be eliminated and the resulting side sway would be serious. Therefore, the present invention includes a stabilizing strut at each side of the scaffold arranged in a very simpe, but effective manner wherein the strut extends with the scaffold to any selected height.

The scaffold may also be retracted to form a very compact unit when not in use. The size of this scaffold will depend upon the type of use contemplated for it. In building construction and maintenance, it may be established by providing a width such that when the scaffold is collapsed, it may be moved through a standard doorway, such as a three foot doorway, and it also can be transferred from floor to floor in a standard elevator. Its length may be from six to eight feet to provide a deck suitable for accommodating two men at a time. A scaffold of this size may easily extend to a height of approximately sixteen feet. This provides a comfortable working height to as much as twenty-two feet.

Referring more particularly to the drawing, the primary features of my improved scaffold will include a rectangular wheel-mounted base B, a lazy-tong elevator E mounted upon the base to be extended thereabove, an actuator A at the base adapted to raise and lower the elevator and a rectangular deck D on top of the elevator. A ladder L is provided for access to the deck when it is extended, but it is contemplated that the ladder may be disconnected from the scaffold when it is retracted as for storage. Also, to render this organization of com ponents stable, the apparatus will include restraining struts S at each side of the scaffold which connects the deck D, to the base and to the ground surface therebelow. As a matter of form, the base, deck, elevator and strut are desirably arranged in symmetry with respect to the longitudinal, vertical, central plane of the unit. For example, with such symmetry, the elevator E consists of two mirror-opposite sets of lazy-tong units with a set being secured to each side of the base to operate in unison with the other as hereinafter further described.

The base B is a rectangular, open frame of structural members, having longitudinally disposed sides 20 and transverse ends 21. This base carries or connects with the elevator, actuator, ladder, struts and with other components as will be described. The sides 20 are channel members with their flanges turned inwardly to form guideways for the elevator members. The transverse ends 21 are also similar channel members and an extra transverse end member 21a is mounted at the front end of the unit to provide a wider surface to better support the actuator mechanisms hereinafter described. These channel members, and other structural members as hereinafter described, may be of structural steel or of aluminum, and the mode of their fabrication may be by welding, riveting, or by any other suitable fabrication process.

This base is carried upon Wheels 22 mounted at the corners of the unit in any suitable manner. Preferably, the wheels at one end of the unit will be caster wheels and those at the other end of the unit will be fixed wheels. Regardless of the type of wheel, each wheel is provided with a lock 23 to secure the scaffold in a fixed position whenever it is being used. Also, as a practical matter, the locks 23 will be supplemented by corner jacks or the like, not shown, to better hold the apparatus in place whenever the elevator is extended upwardly and in use.

To supplement the wheel locks and to better stabilize the scaffold when it is extended upwardly, an outrigger bar 24 extends from each side of the frame. Each outrigger bar is telescopically held in a transversely disposed tubular socket 25 secured to the underside of the frame sides 20 near the center of the unit. When the outrigger bar 24 is not in use, it may be slid into its socket 25 and out of the way. In use, each outrigger bar 24 is slid ontwardly from its socket to a desirable position and a holding jack 26 is fastened to the end of the outrigger arm to bear against the ground surface as best illustrated at FIG. 2.

Each lazy-tong unit of the elevator, the mirror-opposite of the other, is formed as a vertical array of cross bars arranged as inner bars 27 inclined in one direction and outer bar 28, inclined in the other direction. Each inner bar 27 is connected to an opposing outer bar 28 by a pivot 29 at the centers thereof to form a cross bar pair. Each cross bar pair is connected to a cross bar pair above and/or below it by end pivots 30 interconnecting the ends thereof. In the drawing, designating the forward end of the scaffold as at the actuator A, the upper end of an inward bar 27 pivotally connects with the lower end of an outward bar 28 of the pair above it at the forward end of the apparatus and the upper end of an outward bar 28 pivotally connects wtih the lower end of an inward bar 27 of the pair above it at the rearward end of the apparatus. However, this arrangement can be modified and reversed if necessary. To complete this elevator construction, both the center pivots 29 and the end pivots 30 of each lazy-tong unit are formed by transversely disposed rods 31 which hold the units apart and necessitate their operation in unison, the rods 31 being best illustrated at FIG. 2.

The elevator E is illustrated as having four pairs of cross bars in each lazy-tong unit constituting a desirable array, however, such is not at all a limitation. The number of cross bar pairs will depend upon the size of the scaffold and the height to which it is to be extended. However, when the elevator is extended to its full height, it is undesirable to have the bars 27 and 28 crossed to an angle steeper than approximately 60 degrees in order to maintain longitudinal stability of the lazy-tong units.

The bottom ends of the bars 27a and 28a which form the lowermost cross bar pair of each lazy-tong unit are connected to the adjacent side channel 20 of the base. Consonant with the fundamental arrangement of a lazytong extension, one of these bars, the outer bar 28a, is connected to the channel by a pivot and the other, the inner bar 27a, is connected to the channel by a slide. To effect such connections in a centered, balanced manner and with suitable operative clearances, the bottom end of each bar, 27a and 28a, is provided with a right-angle offset, a dog-leg extension 32 which is adapted to extend downwardly from the end of its bar to lie alongside the inward face of the side channel 20. In this manner, the end of each bar 27a and 28a will remain above the channel 20 and the dog-leg extension 32 of the outer bar 28a will be laterally offset from the end of its bar a distance sufficient to permit that bar to lie directly above the channel 20. The extension 32 of the outer bar 28a, near the forward end of the scaffold, is connected to the channel 20 by a pivot 33 having its axis at the center of the channel as illustrated at FIGS. 1 and 2.

The dog-leg extension 32 of the inner bar 27a, extending downwardly alongside the inner face of the side channel 20 near the rearward end of the scaffold, carries a roller 34 which lies between the channel flanges. Accordingly, the flanges of the channel 20 form a way to permit sliding movement of the bottom of the bar 27a towards and away from the bottom of the other bar 28a to effect a raising and lowering of the lazy-tong elevator. Since the inner surfaces of channel flanges are ordinarily inclined, wear plates 35 are located at the inward opposing surfaces of the upper and lower flanges of the channel 20 to provide flat surfaces for the wheels to roll upon, as illustrated at FIGS. 9, 10 and 11.

Each roller 34 is mounted upon its extension 32 on a shaft stub outstanding from the side of the extension and which is formed by a cross shaft 36 extending transversely across the frame to interconnect the two lazy-tong units. The actuator A connects with each side of this shaft 36 adjacent to each dog-leg extension to pull the shaft towards the forward end of the unit in a uniform balanced mannerwith the shaft maintaining its transversely aligned relationship to the apparatus. Thus, the forward movement of the shaft, moving the rollers 34 in their respective ways formed by the channels 20, will cause both lazy-tong elevator units to raise in unison, and it is obvious that this uniform movement with the shaft maintaining its transverse alignment is essential to proper operation of the apparatus.

The actuator A includes a worm gear unit 37 which is centrally mounted upon a transverse shelf 38 in the forward portion of the frame. To provide suitable clearance for components above the worm unit, the shelf, secured to the opposing side channels 20, is underslung to lie below these channels by the use of suitable spacer blocks 39 as illustrated at FIGS. 3 and 9. A worm wheel shaft 40 extends from each side of the gear unit 37 in a transverse, symmetrical pattern with the end of each shaft extension being carried in a bearing 41 which, in turn, is held in a clip 42 mounted upon the shelf 38. Each shaft extension 40 carries a drum 43 wherein a cable 44 is wound to extend to a sheave block 45 secured to one side of the cross shaft 36 as in the manner illustrated at FIGS. 8 and 10. Thence, each cable extends forwardly from its sheave block to a suitable anchor point on the clip 42 adjacent to the worm wheel shaft 40, such giving the apparatus a desirable mechanical advantage.

Rotation of the worm wheel shaft 40 to move the shaft 36 forwardly to raise the elevator E and rearwardly to lower it, as hereinbefore explained, is effected by rotation of the worm shaft 46 of the worm gear which is oriented at right angles to the worm wheel shaft 40 and extends forwardly to the front end of the frame. The worm gear unit 37 may be selected to provide any desired reduction ratio between the worm wheel shaft and the worm gear shaft and accordingly, the torque on the worm gear shaft may be such that the shaft 46 can be easily rotated to lift the elevator, even with a maximum load upon it. Accordingly, should manual operation be contemplated, the shaft 46 may be terminated by a crank. However, the more convenient arrangement, as illustrated, provides for carrying the forward end of this shaft in bearing blocks 47, and mounting a sprocket 48 thereon. A stand 49 is mounted alongside the bearing blocks and carries a crank-shaft 50 whereon a second sprocket 51 is mounted and connected to the sprocket 48 by a drive chain 52. The crankshaft 50 is illustrated with a crank for manual operation; however, it is obvious that the operation may also be motorized as by the common expedient of removing the crank portion of the shaft 50 and connecting therein a reversable electric drill,

The weight of the elevator E and the deck D upon it will ordinarily urge the elevator downwardly with a spreading apart of the ends of the cross bars of the lazytong units. Accordingly, there will be a pull upon the cables 44 at all times and there will be no slack in the lifting mechanism unless an accident, such as a broken cable, were to occur. To avoid the effects of such an accident, a safety locking mechanism is provided which consists of a rack 53 on the top of each side channel 20 adjacent to the lower end of the inner bar 27a and a detent 54 pivotally connected to the lower end of each bar 27a to engage the rack teeth, as in the manner clearly illustrated at FIG. 11. Each detent is mounted to its bar 27a by a stub shaft which constitutes an end of a transverse cross bar 31a, connecting the bottom ends of the bars 27a of both lazy-tong units. Each detent 54 is suitably biased towards engagement with a rack tooth by a spring 55 and the detent may be released from engagement with the rack teeth in various ways whenever it is necessary to lower the elevator. For example, a pull cord 55a may be connected to the detent and extended to any convenient location, as indicated at FIG. 11.

The deck D on top of the elevator, is similar in construction to that of the base, and is formed of frame members which include side channels 20b and end members 21b corresponding to the comparable base members. However, the deck is shorter since space is not needed for any components of the actuator such as the bearing blocks 47 and stand 49. These deck frame members are covered with a top sheet 56 and suitable enclosure means may be provided above this top, as indicated by sideboards 57 and posts 58.

The connection of the lazy-tong units to the deck is substantially the same as the connection to the base although in an opposite direction. The top inner bar 27b and top outer bar 28b of each lazy-tong unit is provided with a dog-leg extension 32b which extends upwardly from the upper end of its bar to lie alongside the inner side of the side channel 20b thereabove. The dog-leg extension at the top of the inner bar 27b, at the forward end of the unit, is pivotally connected to the side channel 20b as at pivot 33b and this pivot 33b is directly above the base pivot 33. The dog-leg extension at the top of the outer bar 28b, at the rearward end of the unit, is provided with a roller 34b, FIG. 4, which is carried between the flanges of the channel 20b in a manner the same as that heretofore described for roller 34 and illustrated at FIGS. 10 and 11. Also, the channel 20b may be provided with wear pads 35b similar to pads 35, heretofore described, although it is unnecessary to provide more than a single pad, at the underside of the top flange of channel 20b, since the weight of the deck will always be downwardly upon the roller.

The ladder L, to provide access to the deck when the scaffold is extended, may be of any standard type, and a convenient type of ladder is illustrated as being located at the rearward end of the scaffold and being formed in three sections which telescopically slide together. To incline this ladder somewhat, the bottom section is secured to the outer end of cantilever arms 59 which are fastened to the end 21 of the base by socket 60 wherein the arms fit. The top of the ladder is secured to the deck D by pins 61 which fit in clevis clips 62 attached to the end member 21b as illustrated. Because of the inclination of the ladder, it will rotate about the pins 61 as the scaffold is lowered and the length of the ladder is changed. It is contemplated that this ladder will be removed whenever the scaffold is retracted to its folded-up position such as illustrated at FIG. 3.

The apparatus, thus far described, is stable and adequately rigid in a longitudinal direction, in the plane of the lazy-tong units of the elevator; however, it is lacking in lateral stability. The necessary lateral stability is provided by one or more compression struts S at each side of the scaffold, and in a scaffold of the size heretofore noted, approximately three feet wide and eight to ten feet long, it was found that a single strut at each side of the unit and near the center thereof was adequate. The top of each strut S is formed with an eye 70 and is connected to clevis clips 71 on the face of a side channel 2011 as by a pin 72. From this connection, each strut extends downwardly and may slope outwardly from the scaffold, to rest upon the ground surface alongside the scaffold. Preferably, the base of the strut is formed by a clevis pad 73 pivotally secured to the bottom of the strut leg as by a pin 74 to better set upon a ground surface. The bottom of the strut leg, however, is also secured to the adjacent side channel 20 by a link 75 which is connected to clevis ears 76 on the side channel 20 by a pin 77 and to the strut leg by a clevis rod 78 rotatably mounted in the leg, as by a pin 79. The pivotal connections of the link 75 facilitate its adjustments when the strut is being connected to the scaffold base as in the manner illustrated.

The primary function of this scaffold is to provide a unit which is adjustable in height, and accordingly, each strut S is formed as a telescopic member, consisting of an outer tubular shell 80 at the base portion, a second tube 80a slidable within the first, a third, 80b slidable within the second, a fourth 80c slidable within the third and a fifth, 80d slidable within the fourth. The eye 70 is located at the top end of this fifth tube 80d. It is to be recognized that the number of these telescopic sections may be varied to be more or less than the five illustrated, and such selection will depend, to a considerable extent, upon the materials available, upon the height to which the strut is to extend and upon the length to which it may be retracted. As a practical matter, it is contemplated that the telescopic strut will not be able to telescope into a unit which is as short as the height of the collapsed scaffold and that the strut at each side of the scaffold will be disconnected as by removing the pin 72, at the top of the strut, as in the manner indicated at FIGS. 3 and 4.

Each telescopic member is preferably formed of square tubing, although round tubing may be used. The top of each member, excepting the top member 80d, is formed with an inner collar 81 and the next-in-sequence tube slidable within such member, actually fits and slides in the collar 81. The next-in-sequence tube has a head 82 about its lower end which fits and slides within the first said tube below the collar 81 and accordingly, the head 82 will contact the collar 81 when the next-in-sequence tube is fully extended as in the manner illustrated at FIG. 6. To complete these sections, rows of holes 83 are formed along their outward and inward faces which are adapted to receive lock pins 84, and a friction lock 85, hereinafter further described, is located near the top of each section excepting the top section 80d.

In the operation of raising the scaffold from a retracted position as illustrated at FIG. 3, the elevator is extended by the actuator A until the upper deck is raised sufiiciently to connect with each strut S. Thereafter, each section is extended, one section at a time, commencing with the top telescopic section 80d. Each section may be extended fully, or partially, as desired, and it is locked in position. The next section will then commence to extend, and so on, until all sections are extended to their desired height and locked.

One mode of locking the sections together is by inserting a lock pin 84 is selected registering holes 83 of two or more of the several sections and, as a matter of safety, this should be done when each section is raised to its selected final position with respect to the adjacent section immediately below it. The holes 83 of the sections arranged in longitudinal rows, move into registration at various positions as the sections are extended, including also, in the fully extended position as indicated at FIG. 6.

Without the friction lock 85, the upward extension of the scaffold is accompanied by a lateral rocking of the deck with one section of the strut sliding in and out of the adjacent section. This rocking action is an undesirable type of mechanical chattering which must be avoided. This is accomplished by the cams 85 which automatically permit the sections 80 to extend as the scaffold is raised, but prevent them from retracting once they are extended, thus eliminating the undesirable in-and-out sliding action. Each cam is formed upon a shaft 86 extending across the outward face of its strut. This shaft is mounted in bearing brackets 87 secured to the opposite sides of the strut section. One end of this shaft turns inwardly 90 degrees to form an arm 88 which lies alongside a side of the strut section. The end of this arm is weighted with a head 89 which imposes a rotative torque on the shaft portion 86. A cam lobe 90 which, preferably has a knurled contacting surface, is secured to the shaft section 86 and is adapted to turn downwardly into a slot 91 in the face of the section, to contact and to compres sively engage with the tubular strut section telescopically fitted within the strut section whereon the cam is mounted. The cam lobe is adjusted on its shaft 86 to tighten against the inner strut section on the downturn of its shaft when the arm 88 is adjusted to be nearly horizontal. Accordingly, the weight of the head tightens the cam and locks the telescoped sections against retraction. However, with this arrangement, the sections may be extended since an extending movement tends to loosen the cam.

In operation, the retracted scaffold is set as a selected location, the wheels 22 are locked in position and corner jacks, not shown, may be used to supplement the wheel locks and if necessary, level the base. Next, the outriggers 24 are set to stabilize the unit. The side struts S are secured to the base B as by the links 75 and their base pads 73 are firmly implanted upon the ground. Next, the scatfold is raised until the top of the struts may be connected to the sides of the deck. Next, the scaffold is raised and as the telescopic sections of the struts are extended, they are either permitted to lock by the friction action of the cams or with pins 84 being inserted into registered holes 83. When at a suitable height, the top of the ladder L may be fitted into the clevis clips 62 and the bottom into the sockets 60. Thereafter, the scaffold may be raised to the desired height for use. When fully extended and locked by the pins 84, the struts form rigid members capable of resisting a substantial compressive force and they are adequate to hold the scaffold stable. Moreover, they supplement the outrigger arms in stabilizing the unit.

The lowering of the scaffold follows an opposite procedure, but in addition, the detents 54 are released as by a pull of the cord 55a. At suitable positions, during lowering, the ladder may be removed and thereafter, the side struts disconnected. Finally, the outriggers 24 may be retracted and the Wheel locks 23 released to permit the scaffold to be moved to the next location.

From the foregoing description, it is apparent that various modifications are possible without changing the basic concepts of the invention disclosed herein. Accordingly, I desire that my protection be limited, not by the constructions illustrated and described, but only by the proper scope of the appended claims.

I claim:

1. An extendable scaffold comprising:

(a) a base stabilized upon the ground surface;

(b) a lazy tong elevator having spaced lazy tong units arranged in spaced parallelism in vertical planes and nounted upon the base for upward extension there- (c) actuator means mounted upon the base adapted to raise and lower said lazy tong elevator from and to the base;

(d) a deck carried by the elevator to be raised and lowered with the raising and lowering of the elevator;

(e) extendable stabilizer strut means extending between the ground surface at the base and the deck at each side of the elevator adapted to extend and retract with the raising and lowering of the deck whereby to stabilize the deck while the elevator is being raised and lowered and to also stabilize the deck after it has been extended; and

(f) releasable locking means associated with each said strut means adapted to permit the corresponding strut means to extend but adapted to lock said strut means against retraction during the extension thereof.

2. In the scaffold defined in claim 1, wherein said base includes side members adapted to support said lazy-tong elevator and said stabilizer strut means are connected to said side members.

3. In the scaffold defined in claim 1, wherein each of said strut means is formed as a plurality of tubular sections telescoped together when the scaffold is retracted to a lowered position and extended as the scaffold is raised, and

said locking means being adapted to lock the sections together when the same are at any selected extended position.

4. In the scaffold defined in claim 3, including further:

a supplemental lock means which comprises holes through said sections which register when the same are extended, and

pins adapted to fit therein.

5. In the scaffold defined in claim 3, wherein:

said locking means comprises a cam on one section adapted to engage another section to prevent the 9 sections from telescoping together when so engaged; and

means adapted to normally urge the cam into engagement with said other section.

6. In the scaffold defined in claim 3, wherein said locking means comprises:

a cam shaft on one section;

a. cam on said shaft adapted to engage the adjacent section responsive to an inward, downward rotation of the shaft; and

an arm on said shaft adapted to be aligned in a generally horizontal position when the cam engages said adjacent section and means adapted to urge the same inwardly and downwardly.

References Cited UNITED STATES PATENTS 3/1884 Dye 182-63 3/1884 Johnson 182-172 10/1903 Cheves 182-148 3/1933 Bonnet 182-148 7/ 1957 Schwalbe.

8/1958 Fridolph.

12/1964 Steed 182-148 US. Cl. X.R. 

